AC GATE ION FILTER METHOD AND APPARATUS

摘要

The present invention uses an AC voltage instead of DC voltage on an ion gate to filter/selectively pass ions. The ions that pass through the AC ion gate can be further separated in a spectrometric instrument. An ion mobility spectrometer using the AC ion gate can achieve better gating performance. For a time of flight ion mobility spectrometer with an AC ion gate, a narrow pulse of selected ions can be passed into a drift tube where they are separated based on their low field ion mobility. Moreover, when the AC voltage at the AC ion gate has a waveform as used for differential ion mobility spectrometry, the time of flight ion mobility spectrometer is converted into a two dimensional separation spectrometer, where ions are first separated based on their high field ion mobility and then further separated based on their low field ion mobility.

主权项

1. A method for operating an ion mobility spectrometer comprising:
(a) ionizing a sample to form sample ions; (b) guiding some of the sample ions toward an ion gate, passing some of the sample ions through the ion gate, and continuously guiding the ions in a drift tube after the ion gate; (c) applying at least one AC voltage to the grid elements of the ion gate to selectively pass at least one kind of sample ions through the ion gate; (d) separating the sample ions in a drift tube